Changes

'''Mozilla-specific things.''' The above loop currently isn't traced, but it should be as that gives a ~1.5x speedup. [https://bugzilla.mozilla.org/show_bug.cgi?id=606890 Bug 606890] is traced and accounts open forthis. Removing unnecessary function guards gains another ~1.15x ([https://bugzilla.mozilla.org/show_bug.cgi?id=606892 Bug 606892]). roughly 95% of execution timeLICM also helps by another ~1.2x ([https://bugzilla.mozilla.org/show_bug.cgi?id=545406 Bug 545406]).